Physicists discover flaws in superconductor theory

April 8, 2016, American Institute of Physics
This image of a magnet levitated over a high-temperature superconductor array shows rectangular TFMs (black) levitating a heavy ferromagnet (silver) above a container of liquid nitrogen. Credit: Weinstein/University of Houston

University of Houston physicists report finding major theoretical flaws in the generally accepted understanding of how a superconductor traps and holds a magnetic field. More than 50 years ago, C.P. Bean, a scientist at General Electric, developed a theoretical explanation known as the "Bean Model" or "Critical State Model."

The basic property of is that they represent zero "resistance" to electrical circuits. In a way, they are the opposite of toasters, which resist electrical currents and thereby convert energy into heat. Superconductors consume zero energy and can store it for a long period of time. Those that store magnetic energy —known as "trapped field magnets" or TFMs—can behave like a magnet.

In the Journal of Applied Physics, the researchers describe experiments whose results exhibited "significant deviations" from those of the Critical State Model. They revealed unexpected new behavior favorable to practical applications, including the possibility of using TFMs in myriad new ways.

Much of modern technology is already based on magnets. "Without magnets, we'd lack generators [electric lights and toasters], motors [municipal water supplies, ship engines], magnetrons [microwave ovens], and much more," said Roy Weinstein, lead author of the study, and professor of physics emeritus and research professor at the University of Houston.

Generally, the performance of a device based on magnets improves as the strength of the magnet increases, up to the square of the increase. In other words, if a magnet is 25 times stronger, the device's performance can range from 25 to 625 times better.

TFMs are clearly intriguing, but their use has been largely held back by the challenge of getting the magnetic field into the superconductor. "A more tractable problem is the need to cool the superconductor to the low temperature at which it superconducts," Weinstein explained.

"Bean assumed the superconductor had zero resistance and that the basic laws of electromagnetism, developed circa 1850, were correct," Weinstein said. "And he was able to predict how and where an would enter a superconductor."

The method widely used today is to apply a magnetic field to a superconductor via a pulse field magnet after the superconductor is cooled. Bean's model predicted, and until now experiments confirmed, that to push as much as possible into a superconductor, the pulsed field must be at least twice as strong, and more typically over 3.2 times as strong, as the resulting field of the TFM.

But, this severely limits the applicability of TFMs. "It's difficult and expensive to produce fields of more than 12 tesla," said Weinstein. "If Bean's theory held true, this cost and practicality barrier would limit TFMs used within products to a maximum of typically 3.75 tesla."

Minor problems with Bean's Critical State Model emerged shortly after it was published, according to Weinstein. Any chink in theoretical armor is worthy of an exploratory experiment, and this is what motivated Weinstein and his colleagues.

They discovered that for certain constraints on a magnetic pulse, Bean's model is far off base, and a significantly different spatial distribution of field occurs. "Great increases in field occur suddenly, in a single leap, whereas Bean's model predicts a steady, slow increase," Weinstein said.

All of this new, unexpected behavior is repeatable and controllable. "The most encouraging is that we can now produce full-strength TFMs with a pulse strength 1.0 times that of the TFM," he added.

"By using our newly discovered methods, the maximum TFM field is now 12 tesla," said Weinstein. "A motor, if made in a fixed size, can produce 3.2 times the torque. Alternatively, the motor can be designed to produce the same amount of torque, but have its volume reduced by more than 10 times. This reduction in materials can result in great cost savings."

The researchers are still within the "early days" of this work and have already disproven their first thoughts concerning what is causing their results. "We're now essentially spelunking in a dark cave without lights—it's frustrating, but exciting," Weinstein said.

In terms of applications for their discovery, the researchers suggest the ability to replace a $100,000 low-temperature superconducting magnet in a research X-ray machine with a $300 TFM, or possibly replace a motor with one that is a quarter of the size of an existing one. There are many other potential applications, such as an energy-efficient ore separator, noncontact magnetic gears that will not wear or require repair, a red blood separator with 50 percent improved yield, and even an automated docking system for spacecraft.

Weinstein and colleagues are now searching for fast, short-term support that will allow them to continue their research to explain this new phenomenon. "While we now know enough to apply our new discovery to significantly improve a large number of devices, we don't yet fully know what's going on in terms of the basic laws of physics," he noted.

Explore further: Breakthrough in superconducting materials opens new path to fusion

More information: "Anomalous results observed in magnetization of bulk high temperature superconductors - a windfall for applications," by Roy Weinstein, Drew Parks, Ravi-Persad Sawh, Keith Carpenter and Kent Davey, Journal of Applied Physics April 7, 2016, DOI: 10.1063/1.4945018

Related Stories

Superconductor survives ultra-high magnetic field

November 12, 2015

Physicists from the universities of Groningen and Nijmegen (the Netherlands) and Hong Kong have discovered that transistors made of ultrathin layers molybdenum disulfide (MoS2) are not only superconducting at low temperatures ...

Superconductivity seen in a new light

March 31, 2016

Superconducting materials have the characteristic of letting an electric current flow without resistance. The study of superconductors with a high critical temperature discovered in the 1980s remains a very attractive research ...

Frustrated magnets point towards new memory

September 23, 2015

Theoretical physicists from the University of Groningen, supported by the FOM Foundation, have discovered that so-called 'frustrated magnets' can produce skyrmions, tiny magnetic vortices that may be used in memory storage. ...

Recommended for you

Bursting bubbles launch bacteria from water to air

November 15, 2018

Wherever there's water, there's bound to be bubbles floating at the surface. From standing puddles, lakes, and streams, to swimming pools, hot tubs, public fountains, and toilets, bubbles are ubiquitous, indoors and out.

Terahertz laser pulses amplify optical phonons in solids

November 15, 2018

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg/Germany presents evidence of the amplification of optical phonons ...

Designer emulsions

November 15, 2018

ETH material researchers are developing a method with which they can coat droplets with controlled interfacial composition and coverage on demand in an emulsion in order to stabilise them. In doing so they are fulfilling ...

Quantum science turns social

November 15, 2018

Researchers in a lab at Aarhus University have developed a versatile remote gaming interface that allowed external experts as well as hundreds of citizen scientists all over the world to optimize a quantum gas experiment ...

12 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

axemaster
3.8 / 5 (8) Apr 08, 2016
The basic property of superconductors is that they represent zero "resistance" to electrical circuits. In a way, they are the opposite of toasters, which resist electrical currents and thereby convert energy into heat.

I can't even count the number of brain cells that died when I read this.

Generally, the performance of a device based on magnets improves as the strength of the magnet increases, up to the square of the increase. In other words, if a magnet is 25 times stronger, the device's performance can range from 25 to 625 times better.

What is this "performance" supposed to be?
gculpex
3.7 / 5 (3) Apr 08, 2016
The basic property of superconductors is that they represent zero "resistance" to electrical circuits. In a way, they are the opposite of toasters, which resist electrical currents and thereby convert energy into heat.

I can't even count the number of brain cells that died when I read this.

LOL
Hyperfuzzy
3 / 5 (2) Apr 08, 2016
Nice, we finally see continuous current as part of the atomic "genome". Current and magnetism related only in timing. That is, charge must change position to create current. Uniform change without nuclear momentum loss, a stable state.

Note: current is always present. The field helps to polarize, once we remove nuclear motion. We could do it with uniform and controlled nuclear motion but this is a high energy superconductor, ambient too hot. Still, define what atomic structure we should use at room temperature. Our sun has a high energy superconductive state. Maybe useful in propulsion! Hyper Light speed!

This is NOT Ohms law. But the causal effects to Ohms law!
compose
Apr 08, 2016
This comment has been removed by a moderator.
compose
Apr 08, 2016
This comment has been removed by a moderator.
c0y0te
5 / 5 (4) Apr 09, 2016
Mentioning toasters two times in an article about superconductivity... Was someone hungry while writing this? :-)
arom
Apr 09, 2016
This comment has been removed by a moderator.
Protoplasmix
3.7 / 5 (3) Apr 09, 2016
Minor problems with Bean's Critical State Model emerged...

uh, one small step for physicists,
one giant [field] leap for TFMs
~ting~ /crackle

uh, roger that, charlie sierra mike is tango uniform, Huston
~ting~ /crackle
dedereu
not rated yet Apr 11, 2016
There is no flaw in the basic superonductivity theory of Cooper pairs , only the crude Bean crititcal current model can be too simple to describe the reality at high critical current in theses complex superconductors with cascade flux penetration.
Hyperfuzzy
not rated yet Apr 27, 2016
University of Houston physicists report finding major theoretical flaws in the generally accepted understanding of how a superconductor traps and holds a magnetic field.

… Much of modern technology is already based on magnets…

... "While we now know enough to apply our new discovery to significantly improve a large number of devices, we don't yet fully know what's going on in terms of the basic laws of physics,"


It seems that we know very little about the theoretical aspect of magnetic field; maybe understand its mechanism could help the research …
http://www.vacuum...21〈=en


kidding, right? we do know. do we apply?
hgdorsey
1 / 5 (1) Apr 29, 2016
There are basic flaws in existing electromagnetic theory. These flaws, whether intentional or not, when corrected will lead to electromagnetic creation of artificial gravity and anti-gravity as well as a number of free energy devices which tap the energy of the magnetic field itself. The chapter on scalar physics in the book "The Covert Colonization of Our Solar System" points out what these flaws are and how to correct them.
Hyperfuzzy
not rated yet Apr 29, 2016
There are basic flaws in existing electromagnetic theory. These flaws, whether intentional or not, when corrected will lead to electromagnetic creation of artificial gravity and anti-gravity as well as a number of free energy devices which tap the energy of the magnetic field itself. The chapter on scalar physics in the book "The Covert Colonization of Our Solar System" points out what these flaws are and how to correct them.

Think you are lost in the relative aspects of the H field vs the E field and particle flow. No flaws, just not an absolute. The particle motion is relative. get it?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.